1. Field of the Invention
This invention relates to spring installing devices for use in general instruments, and more particularly to a device for installing a spring in such a way that its first arm is brought into engagement with a movable member and its second arm is brought into connection with a stationary member to thereby impart into the movable member a resilient force.
2. Description of the Prior Art
The torsion coil springs used in general instruments are usually set with their first arms acting on movable members and with their second arms fixed in position. When it is desired to install a torsion spring in a prescribed position, the two arms of the spring are brought respectively into engagement with the movable and stationary members directly by hand. In the case of high precision instruments such as cameras, because of limitations on the availability of spaces for access and the flexibility of the assembling process, the points in position of the spring which are allowed to contact (particularly at the fixed arm end) are very restricted. Further, upon consideration of the automation of the assembly line for such instruments and improvements in efficiency and reliability, a necessity arises that the torsion coil spring be of a convenient form for installation (for example, symmetrical). In an alternative which is encountered the spring is first built into a certain unit and then, after the installation of this unit in a main body, it is set to operate. In the process for manufacturing such instruments it has been the conventional practice that the installation of the spring is accomplished as close to the final stage of assembly as possible, or that after a certain subsequent unit has been attached to the basic body, the spring is installed. Another method has also been employed wherein the spring is first built into the corresponding unit, and after this unit has been settled in the prescribed position, one arm of the spring is taken from that unit and brought into connection with a fixer adapted therefor manually. The use of these conventional methods limits the range of possible shapes of the spring, or the degree of flexibility of the arrangement of the spring installing step, thereby resulting in disadvantages in the efficiency of assembly whereby reliability is lowered. For a further advance in the automation of the assembly procedure, the existence of the manual labor at the intermediate stage called "spring setting" prohibits a desirable increase in the productivity.
For example, in the roller carrier supported on the framework or back cover of the camera to press the film against the takeup spool in the past the spring has been mounted as illustrated in FIG. 1. That is, in FIG. 1, a roller carrier 21 rotatably bears a roller 23 at journals 22 formed in portions of the body thereof and is supported at a pivot shaft receptor 25 formed in the opposite side to that having the roller 23. This receptor 25 is fitted on shafts (not shown) provided within the camera housing so that the carrier 21 can pivotally move about the shaft. The carrier 21 is further provided with a torsion coil spring 27 surrounding a shaft 26 in a cutout of the receptor 25 whereby the roller 23 is urged in a predetermined direction when the carrier 21 is mounted in the camera housing. And, the roller 23 is arranged to be always pressed against the convoluted film (not shown) on the takeup spool (not shown) to prevent jamming of the film.
With a spring mounting of such construction, when the carrier 21 is to be built into the camera body (not shown), one arm 27a of the spring is necessarily allowed to project to the full length thereof out of the carrier as the opposite arm 27b lies flat on the surface of the carrier. During the installing operation, therefore, it often happens that the arm 27a of the spring 27 interferes with some of the internal parts of the camera body, thus making the installation difficult. For this reason, it has been the common practice in the art that when assembling the carrier 21 within the camera housing, care must be taken of the adjustment in position of the arm 27a. Thus, there has been encountered a very difficult problem automating the assembly line.